new housemate disrupting existing dynamics and fear of him snitching

Here are the key details of the situation:
I am living and working full time in London.
100% Protection from Eviction:
I want to ensure that I am fully protected from eviction under any circumstances, especially considering the potential for issues arising from a new housemate.
The Issue at Hand:
Before the new housemate moved in, my living situation and the upkeep of the flat were perfectly fine. All the tenants were happy, and we lived in a way that worked well for everyone. My landlord, Esme, has never conducted regular property checks and has only intervened if a tenant complains, which never happened before the new housemate moved in recently. However, with the arrival of the new housemate, he has become very particular about cleanliness and tidiness, expecting everyone to behave as he does, which is not how the flat was run before his arrival. I get on so great with the rest of the housemates and they are all so chill.
The new housemate has been washing and tidying others' things without asking and then expecting the same in return. While I agree that we all should pitch in, his approach is becoming unreasonable. I made it clear to him that I would not comply with his demands, and while he understood this, he still continues to fuss about cleanliness and the time things stay out.
In our flatshare, it is understood that we maintain a reasonable standard of cleanliness, but things are not expected to be pristine at all times unless they present a health or safety hazard or cause damage to the property. The new housemate has taken issue with this and has expressed dissatisfaction despite no actual damage being done.
Disruption Caused by the New Housemate:
The new housemate is using his freelance chef job as a reason for his behavior, claiming that he takes pride in his kitchen. However, it is not his kitchen. We were here before him, and he needs to decide if the flatshare is the right fit for him. He should adapt, not attempt to change the established system we had in place.
Additionally, he has been moving our belongings around without asking. He went into all of our cupboards, took our things out without permission, and only asked us if we were okay with things being moved that were left outside. He moved things around randomly, which made it hard for me to find my items, and when I asked in the group chat, there was no response. His justification for this behavior was that he did not throw anything away, but it was still disruptive.
The issue is not with me complying with the tenancy agreement; it’s about the new housemate’s personal preferences causing disruption to the established routine. He’s using his job as a freelance chef as an excuse for his behavior. He’s also creating tension by potentially “snitching” to the landlord, which is unusual in our flat as Esme rarely intervenes unless someone complains.
The level of mess in the flat is typical of a shared living situation, and no health or safety hazards or property damage have been caused.
How I can ensure that my living situation remains unchanged despite the disruption caused by the new housemate?
I would like to continue living in the flat the same way I did before the new housemate moved in, without having to make any changes or adapt my behaviour, as this is causing me stress and affecting my performance at work, risking in me losing my job if I am stressed and don't perform well. I want to ensure I have legal protection from any potential complaints or disputes that may arise from him or any other housemate. He does not have a regular job with regular income, and has a lot of free time on his hands, so he uses that for a sense of control when he is not working, while I have a full time 40 hour work week at my job.
Specifically, I am seeking advice on the following:
How can I ensure 100% protection from eviction if any complaints arise in the future from the new housemate or any other housemate, given that the landlord only intervenes when there is a formal complaint?
What steps can I take to preserve my current living conditions without being forced to comply with the new housemate’s personal preferences?
How can I protect myself from any future retaliation or complaints, especially if the new housemate continues to cause issues based on his personal standards and professional background?